Color diffusion transfer processes using dye releasing redox compounds which can release a diffusible magenta dye as a result of development under basic conditions are well known.
As dye releasing redox compounds which release a magenta dye, those described, for example, in JP-A-49-114424, JP-A-50-115528, JP-A-55-4028, JP-A-61-273542 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"), U.S. Pat. Nos. 3,932,380 and 3,931,144, are known.
However, the compounds as described in these patents contain an azo series dye moiety having a relatively high hydrophobicity and dyes released therefrom have low diffusibility and insufficient spectral characteristic for color reproducibility. From a standpoint of color reproducibility, it has been particularly desired to reduce the subsidiary absorption of dye in a blue light region.